This disclosure relates to a method of manufacturing a catalytic converter.
Catalytic converters are typically employed for the oxidation of carbon monoxide and hydrocarbons and the reduction of oxides of nitrogen in automobile exhaust gas streams. A catalyst disposed on a frangible substrate is supported within the catalytic converter to facilitate the oxidation and reduction process of the exhaust gas stream. During operation, the exhaust gases pass over the substrate and contact the catalyst where the amount of hydrocarbons, carbon monoxide, and oxides of nitrogen are reduced. The temperature of the catalyst is typically between 750xc2x0 C. and 950xc2x0 C. and may be higher depending upon the location of the catalytic converter relative to the engine of the automobile. To lessen the effects of this high temperature, a support material cushions and insulates the catalyst material from a housing in which the substrate and catalyst are mounted.
There are several common conventional methods for making catalytic converters; the xe2x80x9cclamshellxe2x80x9d method, the xe2x80x9ctourniquetxe2x80x9d method, and the xe2x80x9cstuffedxe2x80x9d method. In the clamshell method, the internal end-cones and insulative material are cut to conform with each clam shell half, and the halves of the shell are assembled together by a welding process. The catalytic converters made by this method have reduced durability due to the poor control of the mat support material density.
The xe2x80x9ctourniquetxe2x80x9d method comprises wrapping the shell around the catalyst substrate and support mat assembly. The shell is formed by welding the edges while the assembly is squeezed at rated pressures calculated to optimize the support mat density. The end-cones are then welded to the shell assembly to form the catalytic converter. Although this method also has the disadvantages of increased cost due to the number of components that have to be processed and also the added cost of welding wires and gases, it claims improved mat density control.
The xe2x80x9cstuffedxe2x80x9d (with welded end-cone assemblies) method comprises wrapping the catalyst substrate in the insulative support material and stuffing it, under pressure, into a preformed round shell. The end-cone assemblies with the insulating material are fitted and welded to the shell assembly to form the catalytic converter. Conventional welding techniques have been commonly used to form these catalytic converters.
Conventional welding techniques involve the application of heat to localized areas of two metallic workpieces, which results in a uniting of the two workpieces. This type of welding may or may not be performed with the application of pressure, and may or may not include the use of a filler material. The drawbacks of conventional welding techniques include the creation of a high amount of heat that risks damage to the parts being welded. Another drawback is that dissimilar metals and workpieces of different gauge thicknesses cannot be joined, thereby limiting the materials used in forming catalytic converters. Lastly, these conventional techniques are expensive since they require a welding process that consumes welding wires and costly welding gases.
Accordingly, there remains a need in the art for a method for manufacturing a catalytic converter that is easily welded and cost effective.
The deficiencies of the prior art are overcome or alleviated by the method of producing a catalytic converter.
A method for manufacturing a catalytic converter comprising disposing a first end around a second end and disposing an induction coil around the first end. Discharging a current through the induction coil and forming eddy currents on the outer surface of the first end. This magnetic impulse welds the first end and the second end together such that the first end disposed around the second end comprises a tube end disposed around an end of a catalytic converter or such that the first end disposed around the second end comprises the catalytic converter end disposed around the tube end.
A method for manufacturing a catalytic converter, comprising disposing a catalyst substrate, surrounded by a mat support material, within a shell and disposing an induction coil around the shell. Discharging a current through the induction coil and forming eddy currents on the surface of the shell. Magnetic impulse sizing the shell about the mat support material to size the shell to the mat support material.
A method for manufacturing a catalytic converter comprising disposing a first end around a second end and disposing an induction coil around the first end. Discharging a current through the induction coil and forming eddy currents on the surface of the first end. Magnetic impulse welding the first end and the second end together such that the first end disposed around the second end comprises an endplate end disposed around an end of a shell or wherein the first end disposed around the second end comprises the shell end disposed around the endplate end.